Badge readers are used to control access to certain areas and to restrict the use of certain pieces of equipment such as machinery, computers or vehicles. The badge reader may be adapted to read a magnetic code placed on a badge or to optically detect certain coded information placed on or in the badge.
Frequently it is desirable to maintain an extremely secure access control system. Badges and badge readers that rely exclusively on magnetically encoded data generally are undesirable if security is a major factor because the magnetic information can readily be decoded or altered. Similarly, badge readers that read visible symbols such as numbers, letters or bar codes also cannot be relied upon exclusively when security is a major consideration, because the code can readily be observed, copied and/or altered.
Many electro-optical badge reading devices have been developed which rely upon passing visible light through apertures in a badge. Such devices are shown in U.S. Pat. No. 4,114,028 which issued to Baio et al on Sept. 12, 1978 and is entitled OPTICAL PUNCHED CARD READER; U.S. application Ser. No. 337,490 filed Jan. 6, 1982 by Kenneth R. Wessel and entitled CARD READER WITH AIR PASSAGE CLEANING STRUCTURE; U.S. application Ser. No. 356,046 filed Mar. 8,1982 by Berezowski and entitled ELECTRO-OPTICAL BADGE READER; and U.S. Pat. No. 4,423,317 which issued to Berezowski et al on Dec. 27, 1983 and is entitled MICRO CARD READER. The above identified United States Patents and patent applications are assigned to the assignee of the subject invention. While the electro-optical card readers identified and disclosed in the above cited references are desirable in many instances, they do not provide the high levels of security that often are required. Specifically, the pattern of apertures in a badge can readily be copied or altered thereby affecting the access that is intended to be controlled by the card reader.
Electro-optical card readers have been developed which employ infrared or ultraviolet light that is not visible to the human eye. More particularly, the typical badge for use with an infrared badge reader will be entirely opaque to visible light, but will include portions that are transparent to infrared light. The portions of the badge which transmit infrared are strategically located to define a code that can be read by the appropriate infrared badge reader. Since the entire badge is opaque to visible light, the code cannot readily be determined, copied or altered.
One badge for use with infrared badge readers is shown in U.S. Pat. No. 4,222,662 which issued to Kruegle. The badge shown in U.S. Pat. No. 4,222,662 includes a plurality of layers which are laminated in face to face contact. One of the inner layers includes a code formed from a material which is capable of blocking infrared light. The code shown on the card in U.S. Pat. No. 4,222,662 is disposed between a reflecting surface and a filter which is opaque to visible light but transparent to infrared light. Thus, infrared light is directed through the filter and the code carrying layer, and is reflected off the reflecting material. A read-out device then can assess the coded information as received from the reflective layer in the form of infrared light.
Another card for use with an infrared card reader is shown in U.S. Pat. No. 4,119,361 which issued to Greenaway. The card of U.S. Pat. No. 4,119,361 includes optical markings sandwiched between two protective layers which are transparent to infrared red light but opaque to visible light. The encoded data is printed with very fine lines so as to provide 300 lines per millimeter. This precisely coded data cannot readily be reproduced on infrared photocopying equipment. Additionally, the coded information is so fine that if one or more protective layers is removed from the card, the coded information is likely to be destroyed.
German Auslegeschrift No. 2,856,279 is directed to an identification marker having several layers one of which includes an infrared code. At least a portion of the marker will be destroyed if an attempt is made to delaminate the marker by using water.
European Pat. No. 31-525 also is directed to a multiple layer card with an infrared readable code sandwiched between two covering layers which are bonded together over their entire adjoining surfaces. These covering layers are opaque to visible light and may be formed from PVC foil.
Although the above described infrared badges generally perform well, badges produced from layers that are adhesively bonded to one another often are difficult to manufacture and in certain instances can be delaminated. More particularly, the adhesives must be carefully selected and their use carefully monitored to insure that the adhesive does not affect the code or the adjacent layers. This precise application of adhesive adds time and costs to the manufacturing of such badges. It also is frequently possible to delaminate the adhesively bonded layers to thus expose the code. Attempts to prevent such delamination generally adds significantly to the manufacturing costs. For example, the use of additional reactive layers as taught by Auslegeschrift No. 2856279 or the use of extremely fine codes as taught by U.S. Pat. No. 4,119,361 would significantly add to the cost of each card.
Accordingly it is an object of the subject invention to provide a badge for use with an infrared badge reader which provides enhanced security.
It is another object of the subject invention to provide a badge for use with an infrared badge reader which can be manufactured easily and inexpensively.
It is an additional object of the subject invention to provide a secure badge that cannot be delaminated.
It is of further object of the subject invention to provide a secure badge that does not require adhesives.
It is still an additional object of the subject invention to provide a badge which does not include dissimilar layers of material.